This invention relates to journal bearings for rotating shafts and in particular to bearings which are arranged to support heavy and rapidly rotating shafts in circumstances when abnormal operating conditions may result in uneven contact between their surfaces.
The invention is particularly, but not exclusively, concerned with journal bearings that form a back-up bearing arrangement in which a shaft surface, or a rotating bearing component carried thereon, normally rotates relative to, but spaced from, a stationary part except in circumstances where the means of supporting the shaft with its normal spacing is removed, accidentally or deliberately, or when an external shock or internal out-of-balance imposes loading on the shaft beyond the control of the normal suspension means.
In such circumstances, direct contact between the relatively moving or stationary parts may set up oscillations which prolong and/or effect magnification of the initial impact loading and cause damage to either or both surfaces.
When such contact inevitably leads to stopping rotation of the shaft, direct contact and any resultant damage may be acceptable insofar as bearing surfaces may be replaceable before operation is resumed. However, where impact occurs during shaft rotation without intentional interruption thereof such impact may create such loss of controlled rotation and damage as to require in any event, stopping of the shaft and refurbishment of the bearing.